Recently, a technique of coupling a plurality of control devices (electronic control units: ECUs) with which a motor vehicle has been equipped, to automotive networks (controller area network: CAN) and operating the plurality of control devices in cooperation with each other through the automotive networks, has been developed.
Examples of the plurality of ECUs include an engine ECU that performs control of an engine, a transmission ECU that performs control of shift changing, and a brake ECU that adjusts brake oil pressure. PTL 1 discloses a technique of determining a defect of cooperating operation and specifying a failure area in a case where the plurality of ECUs operates in cooperation with each other.
In particular, PTL 1 discloses a failure diagnosis system including a defect determining means configured to determine occurrence of the defect due to the cooperating operation, based on data transmitted and received between the ECUs through automotive networks, a program acquisition means configured to acquire an inspection diagnosis program previously prepared in correspondence to the defect when the occurrence of the defect is determined, and a failure area specifying means configured to perform the inspection diagnosis program so as to perform corresponding processing to the ECUs, and configured to specify the failure area based on information transmitted from the ECUs by the performance of the corresponding processing.